Low smoke halogen free flame retardant thermoplastic elastomer compositions containing zeolites

ABSTRACT

Halogen-free flame retardant compositions comprising thermoplastic elastomers, which exhibit flame retardance and low-smoke emission. The flame retardant compositions comprise a) one or more thermoplastic elastomers, and b) from at or about 18 to at or about 50 weight percent, the weight percentage being based on the total weight of the flame retardant composition, of a flame retardant mixture comprising: b1) at least one flame retardant comprising a phosphinate, diphosphinate and/or polymers thereof, b2) a phosphorous-containing amino composition; and b3) a zeolite.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.61/448,328, filed Mar. 2, 2011.

FIELD OF THE INVENTION

The present invention relates to the field of low smoke halogen freeflame retardant compositions comprising thermoplastic elastomers.

BACKGROUND OF THE INVENTION

The design flexibility afforded by many thermoplastic resincompositions, their relative light weight and corrosion resistance makethem attractive materials for many uses, including the replacement ofmetal components in many applications including motor and recreationalvehicles, appliances, tools, electronics, furniture, and toys. However,in the construction, furniture, transport or electrical/electronicindustries, thermoplastic resin compositions are preferably made flameretardant to promote product safety, prevent the spread of fire andreduce destruction of products exposed to fire. The conventionalpractice of imparting flame retardance to thermoplastic resincompositions has been the addition of one or more flame retardants or aflame retardant mixture, which typically include a halogenated organiccompound such as brominated polystyrene as the flame retardant and anantimony compound as a synergist for the retardant.

However, halogenated flame retardants tend to decompose or degrade atthe processing temperatures of thermoplastic resins, which implicatespotential health and environmental effects due to the gases that arereleased. Consequently, there has been a trend away from usinghalogenated compounds or mixtures containing them to impart flameretardance.

Another conventional approach to impart flame retardance tothermoplastic resin compositions has been the addition of redphosphorus. Int'l. Pat. App. Pub. No. WO 92/20731 discloses acomposition comprising an elastomer, a flame retardant comprising redphosphorus and ammonium polyphosphate as a flame retardant synergist.Moreover, the use of fine red phosphorus powder homogeneously dispersedin the resin is known and practiced. In addition to the hazards of fireand explosion related to handling fine red phosphorus powders, the verycombustion of red phosphorus causes the emission of toxic fumes due tothe formation of phosphine.

To avert the hazards of using halogenated flame retardants and redphosphorus, phosphinate salts, that is, salts of phosphinic acids, alsoknown as phosphinates, have been substituted in thermoplastic resincompositions. DE Pat. Nos. 2,252,258 and 2,447,727 disclose phosphinatesused as flame retardants. U.S. Pat. No. 4,180,495 discloses is the useof poly(metal phosphinate) salts in flame retardant polyesters andpolyamides. U.S. Pat. No. 6,255,371 discloses flame retardantcompositions comprising a) phosphinates, diphosphinates, or polymers ofthese and b) condensation products of melamine, reaction products ofmelamine with phosphoric acid, reaction products of condensationproducts of melamine with phosphoric acid and/or mixtures of these. U.S.Pat. No. 6,270,560 discloses salt mixtures made from aluminumphosphinates, aluminum hydroxide, aluminum phosphonates and/or aluminumphosphates suitable as flame retardants for polymeric moldingcompositions. U.S. Pat. Nos. 5,780,534 and 6,013,707 disclose flameretardant polyester compositions containing calcium or aluminum salts ofphosphinic acid or disphosphinic acid.

A disadvantage of using halogen-free, flame retardant compositions isthat, upon exposure to flame, such compositions emit a high level ofsmoke, which can cause smoke inhalation hazards severe enough to requireevacuation of the workplace. Therefore, a need remains for halogen-free,flame retardant compositions comprising thermoplastic elastomers whichexhibit the desired flame retardance as well as low smoke emissionproperties.

SUMMARY OF THE INVENTION

The present invention is directed to flame retardant polymercompositions comprising:

-   -   a) one or more thermoplastic elastomers; and    -   b) from at or about 18 to at or about 50 weight percent, based        on the total weight of the flame retardant polymer composition,        of a flame retardant mixture comprising:        -   b1) at least one flame retardant comprising a material            selected from the group consisting of phosphinates of the            formula (I); diphosphinates of the formula (II); polymers of            (I); polymers of (II); and mixtures of two or more thereof;

-   -   -   -   wherein R₁ and R₂ are independently selected from                hydrogen, linear or branched C₁-C₆ alkyl groups, and                aryl groups; R₃ is a linear or branched C₁-C₁₀-alkylene                group, a C₆-C₁₀ arylene group, or an alkylarylene or                arylalkylene group; M is selected from the group                consisting of calcium, magnesium, aluminum, zinc and                mixtures thereof; m is 2 to 3; n is 1 or 3; and x is 1                or 2;

        -   b2) a phosphorous-containing amino composition selected from            the group consisting of melamine phosphates, derivatives of            melamine phosphates and mixtures thereof; reaction products            of ammonia with phosphoric acid, polyphosphates of said            reaction products, and mixtures thereof; and

        -   b3) a zeolite

        -   wherein i) b1) is present in the flame retardant polymer            composition in an amount greater than or equal to 15 weight            percent based on the total weight of the flame retardant            polymer composition, and ii) b2) is present in the flame            retardant mixture in an amount such that the amount of b2)            is less than the amount of b1).

Preferably, the thermoplastic polyester elastomer is a copolyetheresterelastomer.

In a preferred embodiment, the phosphorous-containing amino compositionb2) is melamine pyrophosphate, melamine polyphosphate, or ammoniumpolyphosphate, preferably ammonium polyphosphate and in an even morepreferred embodiment, the amount of ammonium polyphosphate is greaterthan 2 weight percent based on the total weight of the flame retardantpolymer composition.

In an even more preferred embodiment, the flame retardant polymercomposition comprises from at or about 18 to at or about 50 weightpercent, preferably from at or about 20 to at or about 40 weight percentof the flame retardant mixture described above wherein b1) is present inthe flame retardant mixture in an amount of from at or about to at orabout 25 weight percent, b2) is present in the flame retardant mixturein an amount from at or about 5 to at or about 25 weight percent and b3)is present in the flame retardant mixture in an amount from at or about5 to at or about 20 weight percent, the percentage being based on thetotal weight of the flame retardant polymer composition.

Also described herein are molded, extruded, or shaped articlescomprising the flame retardant composition described above. Furtherdescribed herein are wires or cables comprising a coating made of theflame retardant compositions described herein.

In addition, the invention is directed to a flame retardant compositioncomprising

-   -   A) at least one flame retardant comprising a material selected        from the group consisting of phosphinates of the formula (I);        diphosphinates of the formula (II); polymers of (I); polymers of        (II); and mixtures of two or more thereof;

-   -   -   wherein R₁ and R₂ are independently selected from hydrogen,            linear or branched C₁-C₆ alkyl groups, and aryl groups; R₃            is a linear or branched C₁-C₁₀ alkylene group, a            C₆-C₁₀arylene group, or an alkylarylene or an arylalkylene            group; M is selected from the group consisting of calcium,            magnesium, aluminum, zinc and mixtures thereof; m is 2 to 3;            n is 1 or 3; and x is 1 or 2,

    -   B) a phosphorous-containing amino composition selected from the        group consisting of reaction products of ammonia with phosphoric        acid, polyphosphates of said reaction products, and mixtures        thereof; and

    -   C) a zeolite

    -   wherein A) is present in the flame retardant composition in an        amount from at or about 30 to at or about 85 weight percent, B)        is present in the flame retardant composition in an amount        greater than 10 to at or about 30 weight percent, and C) is        present in the flame retardant composition in an amount from at        or about 10 to at or about 40 weight percent, provided that the        sum A)+B)+C) is 100 weight percent.

Also described herein are uses of flame retardant compositions describedherein for imparting flame retardance and low smoke emission tocompositions comprising thermoplastic elastomers.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are to be used to interpret the meaning of theterms discussed in the description and recited in the claims.

As used herein, the article “a” indicates one as well as more than oneand does not necessarily limit its referent noun to the singular.

As used herein, the terms “about” and “at or about” mean that the amountor value in question may be the value designated or some other valuethat is approximately or about the same. The phrase is intended toconvey that similar values promote equivalent results or effectsaccording to the invention.

The one or more thermoplastic elastomers suitable for use in the flameretardant compositions described herein are preferably present in thecompositions of the invention in an amount from at or about 50 to at orabout 80 weight percent, the weight percentage being based on the totalweight of the flame retardant polymer composition, i.e. the sum of thethermoplastic elastomer component, flame retardant mixture component(i.e. the component comprising a flame retardant comprising a materialselected from the group of phosphinates of formula (I), diphosphinatesof formula (II), polymers thereof, and mixtures thereof, thephosphorous-containing amino composition, and, zeolite component and anyoptional components). This may also be expressed as the sum of componenta)+b1)+b2)+b3) plus any optional components.

Preferably, the one or more thermoplastic elastomers in the flameretardant compositions described herein includes those defined in ISO18064:2003(E). Thermoplastic elastomers defined in ISO 18064:2003(E)include copolyester thermoplastic elastomers (TPC), thermoplasticpolyimide copolymers (TPA), thermoplastic polyolefinic elastomers (TPO),styrenic thermoplastic elastomers (TPS), thermoplastic polyurethanes(TPU), and mixtures of these.

Copolyester thermoplastic elastomers (TPC) include copolyesteresterelastomers or copolycarbonateester elastomers, copolyesterester urethaneelastomers, and copolyetherester elastomers, the latter being preferred.

Copolyesterester elastomers are block copolymers containing a) hardpolyester segments and b) soft and flexible polyester segments. Examplesof hard polyester segments are polyalkylene terephthalates,poly(cyclohexanedicarboxylic acid cyclohexanemethanol). Examples of softpolyester segments are aliphatic polyesters, including polybutyleneadipate, polytetramethyladipate and polycaprolactone. Thecopolyesterester elastomers contain blocks of ester units of a highmelting polyester and blocks of ester units of a low melting polyesterwhich are linked together through ester groups and/or urethane groups.Copolyesterester elastomers comprising urethane groups may be preparedby reacting the different polyesters in the molten phase, after whichthe resulting copolyesterester is reacted with a low molecular weightpolyisocyanate such as for example diphenylmethylene diisocyanate.

Copolycarbonateester elastomers are block copolymers containing a) hardsegments consisting of blocks of an aromatic or semi-aromatic polyesterand b) soft segments consisting of blocks of a polycarbonate-containingpolymeric component. Suitably, the copolycarbonateester elastomercomprises hard polyester segments made up of repeating units derivedfrom an aromatic dicarboxylic acid and an aliphatic diol, and softsegments comprising repeating units of an aliphatic carbonate, and/orsoft segments comprising randomly distributed repeating units of analiphatic carbonate and either an aliphatic diol and an aliphaticdicarboxylic acid or a lactone, or a combination thereof, wherein thehard segments and the soft segments can be connected with a urethanegroup. These elastomers and their preparation are described in, e.g. EPPat. No. 0846712.

Copolyetherester elastomers are the preferred thermoplastic elastomersin the flame retardant compositions of the present invention and have amultiplicity of recurring long-chain ester units and short-chain esterunits joined head-to-tail through ester linkages, said long-chain esterunits being represented by formula (A):

and said short-chain ester units being represented by formula (B):

whereinG is a divalent radical remaining after the removal of terminal hydroxylgroups from poly(alkylene oxide)glycols having a number averagemolecular weight of between about 400 and about 6000, or preferablybetween about 400 and about 3000;R is a divalent radical remaining after removal of carboxyl groups froma dicarboxylic acid having a molecular weight of less than about 300;D is a divalent radical remaining after removal of hydroxyl groups froma diol having a molecular weight less than about 250.

As used herein, the term “long-chain ester units” as applied to units ina polymer chain refers to the reaction product of a long-chain glycolwith a dicarboxylic acid. Suitable long-chain glycols are poly(alkyleneoxide) glycols having terminal (or as nearly terminal as possible)hydroxy groups and having a number average molecular weight of fromabout 400 to about 6000, and preferably from about 600 to about 3000.Preferred poly(alkylene oxide)glycols include poly(tetramethyleneoxide)glycol, poly(trimethylene oxide)glycol, poly(propyleneoxide)glycol, poly(ethylene oxide)glycol, copolymer glycols of thesealkylene oxides, and block copolymers such as ethylene oxide-cappedpolypropylene oxide)glycol. Mixtures of two or more of these glycols canbe used.

As used herein, the term “short-chain ester units” as applied to unitspolymer chain of the copolyetheresters refers to low molecular weightcompounds or polymer chain units having molecular weights less thanabout 550. They are made by reacting a low molecular weight diol or amixture of diols (molecular weight below about 250) with a dicarboxylicacid to form ester units represented by Formula (B) above.

Included among the low molecular weight diols which react to formshort-chain ester units suitable for use for preparing copolyetherestersare acyclic, alicyclic and aromatic dihydroxy compounds. Preferredcompounds are diols with about 2-15 carbon atoms such as ethylene,propylene, isobutylene, tetramethylene, 1,4-pentamethylene,2,2-dimethyltrimethylene, hexamethylene and decamethylene glycols,dihydroxycyclohexane, cyclohexane dimethanol, resorcinol, hydroquinone,1,5-dihydroxynaphthalene, and the like. Especially preferred diols arealiphatic diols containing 2-8 carbon atoms, and a more preferred diolis 1,4-butanediol. Included among the bisphenols which can be used arebis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)methane, andbis(p-hydroxyphenyl)propane. Equivalent ester-forming derivatives ofdiols are also useful (e.g., ethylene oxide or ethylene carbonate can beused in place of ethylene glycol or resorcinol diacetate can be used inplace of resorcinol).

As used herein, the term “diols” includes equivalent ester-formingderivatives such as those mentioned. However, any molecular weightrequirements refer to the corresponding diols, not their derivatives.

Dicarboxylic acids that can react with the foregoing long-chain glycolsand low molecular weight diols to produce the copolyetheresters arealiphatic, cycloaliphatic or aromatic dicarboxylic acids of a lowmolecular weight, i.e., having a molecular weight of less than about300. The term “dicarboxylic acids” as used herein includes functionalequivalents of dicarboxylic acids that have two carboxyl functionalgroups that perform substantially like dicarboxylic acids in reactionwith glycols and diols in forming copolyetherester polymers. Theseequivalents include esters and ester-forming derivatives such as acidhalides and anhydrides. The molecular weight requirement pertains to theacid and not to its equivalent ester or ester-forming derivative.

Thus, an ester of a dicarboxylic acid having a molecular weight greaterthan 300 or a functional equivalent of a dicarboxylic acid having amolecular weight greater than 300 are included provided thecorresponding acid has a molecular weight below about 300. Thedicarboxylic acids can contain any substituent groups or combinationsthat do not substantially interfere with copolyetherester polymerformation and use of the copolyetherester polymer in the flame retardantcompositions of the invention.

As used herein, the term “aliphatic dicarboxylic acids” refers tocarboxylic acids having two carboxyl groups each attached to a saturatedcarbon atom. If the carbon atom to which the carboxyl group is attachedis saturated and is in a ring, the acid is cycloaliphatic. Aliphatic orcycloaliphatic acids having conjugated unsaturation often cannot be usedbecause of homopolymerization. However, some unsaturated acids, such asmaleic acid, can be used.

As used herein, the term “aromatic dicarboxylic acids” refer todicarboxylic acids having two carboxyl groups each attached to a carbonatom in a carbocyclic aromatic ring structure. It is not necessary thatboth functional carboxyl groups be attached to the same aromatic ringand where more than one ring is present, they can be joined by aliphaticor aromatic divalent radicals or divalent radicals such as —O— or —SO₂—.Representative useful aliphatic and cycloaliphatic acids that can beused sebacic acid; 1,3-cyclohexane dicarboxylic acid; 1,4-cyclohexanedicarboxylic acid; adipic acid; glutaric acid;4-cyclohexane-1,2-dicarboxylic acid; 2-ethylsuberic acid;cyclopentanedicarboxylic acid, decahydro-1,5-naphthylene dicarboxylicacid; 4,4′-bicyclohexyl dicarboxylic acid; decahydro-2,6-naphthylenedicarboxylic acid; 4,4′-methylenebis(cyclohexyl)carboxylic acid; and3,4-furan dicarboxylic acid. Preferred acids are cyclohexanedicarboxylic acids and adipic acid.

Representative aromatic dicarboxylic acids include phthalic,terephthalic and isophthalic acids; bibenzoic acid; substituteddicarboxy compounds with two benzene nuclei such asbis(p-carboxyphenyl)methane; p-oxy-1,5-naphthalene dicarboxylic acid;2,6-naphthalene dicarboxylic acid; 2,7-naphthalene dicarboxylic acid;4,4′-s sulfonyl dibenzoic acid and C₁-C₁₂ alkyl and ring substitutionderivatives thereof, such as halo, alkoxy, and aryl derivatives. Hydroxyacids such as p-(beta-hydroxyethoxy)benzoic acid can also be usedprovided an aromatic dicarboxylic acid is also used.

Aromatic dicarboxylic acids are a preferred class for preparing thecopolyetherester elastomers useful for this invention. Among thearomatic acids, those with 8-16 carbon atoms are preferred, particularlyterephthalic acid alone or with a mixture of phthalic and/or isophthalicacids.

The copolyetherester elastomer preferably comprises from at or about 15to at or about 99 weight percent short-chain ester units correspondingto Formula (B) above, the remainder being long-chain ester unitscorresponding to Formula (A) above. More preferably, thecopolyetherester elastomers comprise from at or about 20 to at or about95 weight percent, and even more preferably from at or about 50 to at orabout 90 weight percent short-chain ester units, where the remainder islong-chain ester units. More preferably, at least about 70% of thegroups represented by R in Formulae (A) and (B) above are 1,4-phenyleneradicals and at least about 70% of the groups represented by D inFormula (B) above are 1,4-butylene radicals and the sum of thepercentages of R groups which are not 1,4-phenylene radicals and Dgroups that are not 1,4-butylene radicals does not exceed 30%. If asecond dicarboxylic acid is used to prepare the copolyetherester,isophthalic acid is preferred and if a second low molecular weight diolis used, ethylene glycol, 1,3-propanediol, cyclohexanedimethanol, orhexamethylene glycol are preferred.

A blend or mixture of two or more copolyetherester elastomers can beused. The copolyetherester elastomers used in the blend need not on anindividual basis come within the values disclosed hereinbefore for theelastomers. However, the blend of two or more copolyetheresterelastomers must conform to the values described herein for thecopolyetheresters on a weighted average basis. For example, in a mixturethat contains equal amounts of two copolyetherester elastomers, onecopolyetherester elastomer can contain 60 weight percent short-chainester units and the other resin can contain 30 weight percentshort-chain ester units for a weighted average of 45 weight percentshort-chain ester units.

Preferred copolyetherester elastomers include, but are not limited to,copolyetherester elastomers prepared from monomers comprising (1)poly(tetramethylene oxide)glycol; (2) a dicarboxylic acid selected fromisophthalic acid, terephthalic acid and mixtures thereof; and (3) a diolselected from 1,4-butanediol, 1,3-propanediol and mixtures thereof, orfrom monomers comprising (1) poly(trimethylene oxide)glycol; (2) adicarboxylic acid selected from isophthalic acid, terephthalic acid andmixtures thereof; and (3) a diol selected from 1,4-butanediol,1,3-propanediol and mixtures thereof, or from monomers comprising (1)ethylene oxide-capped polypropylene oxide)glycol; (2) a dicarboxylicacid selected from isophthalic acid, terephthalic acid and mixturesthereof; and (3) a diol selected from 1,4-butanediol, 1,3-propanedioland mixtures thereof.

Preferably, the copolyetherester elastomers described herein areprepared from esters or mixtures of esters of terephthalic acid and/orisophthalic acid, 1,4-butanediol and poly(tetramethylene ether)glycol orpoly(trimethylene ether)glycol or ethylene oxide-capped polypropyleneoxide glycol, or are prepared from esters of terephthalic acid, e.g.dimethylterephthalate, 1,4-butanediol and poly(ethylene oxide)glycol.More preferably, the copolyetheresters are prepared from esters ofterephthalic acid, e.g. dimethylterephthalate, 1,4-butanediol andpoly(tetramethylene ether)glycol.

As a result of their excellent tear strengths, tensile strengths, flexlives, abrasion resistances, and broad useful end-use temperatureranges, thermoplastic polyetherester elastomers are used in a wide rangeof applications including for example wire and cable coatings,automotive applications, components for household appliances, componentsfor buildings or mechanical devices and tubes and pipes for conveyingfluids. Examples of suitable copolyetherester elastomers arecommercially available under the trademark Hytrel® from E. I. du Pont deNemours and Company, Wilmington, Del.

Thermoplastic polyamide copolymers (TPA's) consist of copolymerscontaining a) hard polyamide segments and b) soft and flexible segments.Examples of TPA's include polyesteramides (PEA's), polyetheresteramides(PEEA's), polycarbonate-esteramides (PCEA's) and polyether-block-amides(PE-b-A's). Preferably, the TPA consists of a linear and regular chainof polyamide segments and flexible polyether or polyester segments orsoft segments with both ether and ester linkages as represented byformula (C):

wherein“PA” represents a polyamide sequence and “PE” represents for example apolyoxyalkylene sequence formed from linear or branched aliphaticpolyoxyalkylene glycols or a long-chain polyol with either ether orester or both linkages and mixtures thereof or copolyethers orcopolyesters derived therefrom. The polyamide may be aliphatic oraromatic. The softness of the copolyetheramide or the copolyesteramideblock copolymers generally decreases as the relative amount of polyamideunits is increased. Examples of thermoplastic polyamide block copolymerssuitable for use in the compositions of the invention are commerciallyavailable from Arkema or Elf Atochem under the trademark Pebax®.

Thermoplastic polyolefinic elastomers (TPO's) consist of certain rubberyolefin-type polymers, for example propylene or polyethylene, as well asthermoplastics blended with a rubber. Examples of thermoplasticpolyolefinic elastomers (TPO's) include random block copolymers such asalpha-olefin copolymers, including ethylene-propylene copolymers (EPM),ethylene propylene diene copolymers (EPDM), copolymers of ethylene orpropylene or butene with higher alpha-olefin copolymers (e.g.ethylene-hexene, ethylene-octene (for example Engage® which iscommercially available from The Dow Chemical Co.)); random stereoblockpolypropylene; hydrogenated diene block copolymers such as hydrogenatedpolybutadiene and hydrogenated polyisoprene, a mixture of hydrogenatedpolybutadiene and polybutadiene; graft copolymers such asEPDM-g-polypivalolactone (PPVL). Other examples are polyolefin blendthermoplastic elastomers such as for example blends of EPM or EPDM withisotactic polypropylene (iPP), and blends of EPM or EPDM withpolyethylene and polypropylene.

Styrenic thermoplastic elastomers (TPS's) consist of block copolymers ofstyrene and rubbery polymeric materials like for example polybutadiene(TPS-SBS), a mixture of hydrogenated polybutadiene and polybutadiene,poly(ethylene-butylene) (TPS-SEES), polyisoprene (TPS-SIS) andpolyethylene-propylene) (TPS-SEPS).

Thermoplastic polyurethanes (TPU's) consist of linear segmented blockcopolymer composed of hard segments comprising polyisocyanate and achain extender and soft segments comprising diisocyanate and a longchain polyol as represented by the general formula (D):

wherein“X” represents a hard segment comprising a polyisocyanate and a chainextender, preferably a short-chain glycol, “Z” represents a soft segmentcomprising a polyisocyanate and a long-chain polyol and “Y” representsthe residual group of the polyisocyanate compound of the urethane bondlinking the X and Z segments. Preferably, the polyisocyanate is adiisocyanate. Examples of diisocyanate are 4,4′-diphenylmethanediisocyanate (MDI), toluene diisocyanate (TDI), hexamethylenediisocyanate (HDI), 4,4′-dicyclohexylmethane diisocyanate (H12-MDI),trans-trans-4,4′-dicyclohexylmethane diisocyanate, biphenyl diisocyanate(TODI) and 1,4-benzene diisocyanate. The long-chain polyol includesthose of a polyether type such as poly(alkylene oxide)glycol or those ofpolyester type.

Flame retardance in the flame retardant thermoplastic elastomercompositions described herein is imparted by flame retardant mixturesalso referred herein as flame retardant compositions. These flameretardant mixtures b) comprise a flame retardant b1) which is aphosphinate of the formula (I) (i.e. a monophosphinate) and/or adiphosphinate of the formula (II) and/or polymers of (I) and/or (II),

wherein R₁ and R₂ are identical or different and are hydrogen, linear orbranched C₁-C₆ alkyl groups, and/or aryl groups; R₃ is a linear orbranched C₁-C₁₀-alkylene group, a C₆-C₁₀-arylene group, an alkylarylenegroup or arylalkylene group; M is calcium, magnesium, aluminum, and/orzinc; m is 2 to 3; n is 1 or 3; and x is 1 or 2.

R₁ and R₂ may be identical or different and are preferably hydrogen,methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl and/orphenyl. R₃ is preferably methylene, ethylene, n-propylene, isopropylene,n-butylene, tert-butylene, n-pentylene, n-octylene, n-dodecylene, orphenylene or naphthylene, or methylphenylene, ethylphenylene,tert-butylphenylene, methylnaphthylene, ethylnaphthylene ortert-butylnaphthylene, or phenylmethylene, phenylethylene,phenylpropylene or phenylbutylene. M is preferably aluminum or zinc.

By polymers of the compounds of formulas (I) and (II) is meant speciescontaining oligomers or condensation products of the phosphinate anddiphosphinate anion moieties.

Preferred phosphinates are metal salts of organic phosphinates, such asmetal salts of methylethylphosphinates and diethylphosphinates. Morepreferred are aluminum methylethylphosphinate, aluminumdiethylphosphinate, zinc methylethylphosphinate, and zincdiethylphosphinate. More preferably, the flame retardant is aluminumphosphinate, magnesium phosphinate, calcium phosphinates and/or zincphosphinate and still more preferably, the flame retardant is aluminumphosphinate, aluminum diethyl phosphinate and/or zinc diethylphosphinate.

Although the flame retardant composition may contain both a phosphinateand a diphosphinate or a diphosphinate alone, preferred compositionscontain monophosphinates due to cost and availability.

The flame retardant b1) is usually in the form of particles which mayhave any particle size distribution, as commonly understood and used bythose having skill in the field, but preferably the phosphinate and/ordiphosphinates that comprise component b1) have particle sizes (D90value) of less than or equal to 100 microns and more preferably lessthan or equal to 20 microns. The D90 value corresponds to a particlesize below which 90 weight percent of the particles lie, wherein theparticle size distribution is measured by the technique of laserdiffraction from a suspension of particles in a solvent using a particlesize analyzer; Mastersizer 2000 from Malvern. This test method meets therequirements set forth in ISO 13320.

Preferably, the flame retardant mixtures b) comprise a flame retardantb1) in an amount from at or about 30 to at or about 85 weight percent,the weight percentage being based on the total weight of the flameretardant mixture, i.e. the sum of components b1)+b2)+b3).

The flame retardant mixtures b) described herein comprise aphosphorous-containing amino composition, b2), that is a melaminephosphate, a derivative of a melamine phosphate or mixtures thereof, areaction product of ammonia with phosphoric acid or a polyphosphatethereof, for example melamine pyrophosphate or ammonium polyphosphate ormixtures thereof, in an amount such that the amount of b2) is lower thanthe amount of b1). Preferably the amount of b2) is greater than 10 to ator about 30 weight percent, the weight percentage being based on thetotal weight of the flame retardant mixture, i.e. the sum of componentsb1) b2) b3). Suitable phosphorous-containing amino compositions that arereaction products of ammonia with phosphoric acid or a polyphosphatederivative thereof include ammonium hydrogenphosphate, ammoniumdihydrogenphosphate and ammonium polyphosphate. More preferably, thephosphorous-containing amino compositions comprises melaminepyrophosphate or ammonium polyphosphate. Suitable phosphorous-containingamino compositions that are melamine phosphates include melamineorthophosphate (C₃H₆N₆H₃O₄P), dimelamine orthophosphate (C₃H₆N₆H₃O₄P)₂,melamine polyphosphate, dimelamine pyrophosphate, and melaminepyrophosphate. Derivatives of melamine phosphates include, for example,melem polyphosphate, melam polyphosphate and melamine borophosphates.

The material known as melamine pyrophosphate is a compound defined bythe nominal formula (C₃H₆N₆)₂H₄P₂O₇. Commercially available grades ofmelamine pyrophosphate may have substantial impurities in terms ofhaving a different ratio of phosphorous to nitrogen and/or containingother phosphorous containing anions. See U.S. Pat. No. 5,814,690.Nevertheless, any compound having the nominal melamine pyrophosphateformula above or sold commercially as melamine pyrophosphate is suitablefor use in the flame retardant compositions of the invention and fallswithin the scope of the recited invention.

The phosphorous-containing amino composition may also comprise coatedparticles, for example particles that have a core comprising melaminepyrophosphate and a coating comprising an organosilane, ester, polyol,dianhydride, dicarboxylic acid, melamine formaldehyde, or mixturesthereof. Such coated compositions are disclosed in U.S. Pat. No.6,015,510, the teaching of which is incorporated herein by reference. Anexample of a suitable coated melamine pyrophosphate is a melaminepyrophosphate coated with 0.6±0.1 wt. % Silquest® A-1100 silane.Alternatively, the coating agent may be added to thephosphorous-containing composition in a separate step prior to blendingwith one or more components of the composition of the invention or in astep wherein all components are mixed together. In such cases, theamount of coating agent will generally be in the range of from about 0.1to about 6 wt. %, based on the weight of the coatedphosphorous-containing composition.

The flame retardant mixture b) described herein also comprises from ator about 10 to at or about 40 weight percent of a zeolite b3), theweight percentage being based on the total weight of the flame retardantmixture, i.e. the sum of components b1) b2) b3). Zeolites are hydroustectosilicate minerals characterized by a three-dimensionalaluminosilicate tetrahedral framework. The framework contains channelsand interconnected voids occupied by ion-exchangeable cations andloosely held water molecules permitting reversible dehydration.Preferred zeolites are represented by the general formula (III):

M_(2/n)O.Al₂O₃ .xSiO₂ .yH₂O  (III)

whereinM is a metal selected from alkali and alkaline earth metals, V, Mo, Mn,Fe, Co, Ni, Cu, Zn, Sb, Bi and mixtures thereof;n is the cation valence;x is from 0.1 and 20; andy is the number of moles of water of crystallization and has a value of0 to 20.

The zeolite b3) component may be naturally occurring or syntheticallyprepared. Examples of naturally occurring zeolites include analcite,analcime, cancrinite, chabazite, clinoptilolite, erionite, faujacite,heulandite, mordenite, natrolite, nosean, phillipsite and stilbite.Particularly suitable is a zeolite Y type.

It is generally preferred that zeolites are used in the form having anequilibrium moisture content, which is generally around 20-30 wt. %,based on the weight of the zeolite. Oven-drying may alter the porestructure of the zeolite, which is undesirable.

The flame retardant composition comprising the three components b1), b2)and b3) is itself a novel composition that may be used as an intumescentadditive in a variety of polymeric compositions wherein flame retardanceand smoke suppression is desired. Intumescence refers to a specificchemical reaction described as the formation, during combustion, of afoaming char instead of combustible gases. The charred layer serves as aphysical barrier, which slows down heat and mass transfer between thegas and the condensed phases. The composition may be used to impartflame retardancy and smoke suppression properties to a wide range ofpolymers, for example thermoplastics, elastomers and thermoplasticelastomers, including thermoplastic vulcanizates, copolyesterthermoplastic elastomers, thermoplastic polyamide copolymers,thermoplastic polyolefinic elastomers, styrenic thermoplasticelastomers, thermoplastic polyurethanes, copolyetherester elastomers,copolyesterester elastomers, polychloroprene, EPDM rubber,fluoroelastomers and ethylene acrylic elastomers.

The phosphorus-containing amino composition b2) in the flame retardantmixture described herein is preferably used in combination with otheringredients to form an intumescent system, i.e. thephosphorus-containing amino composition b2) is comprised in theintumescent system. The intumescent system comprises at least threecomponents; b2) as an acid source; a carbonific agent; and a spumificagent.

The acid source, the carbonific agent and the spumific agent may, incertain instances, be the same chemical compound. In such instances, thecompound will function as one or more of acid source, carbonific agentand spumific agent. For example, melamine polyphosphate can act as anacid source and a blowing agent. When an intumescent system comprisingthe phosphorus-containing amino composition b2) described herein is usedin the flame retardant mixtures described herein, the intumescent systemis generally present in the flame retardant mixture in an amount from ator about 15 to at or about 70 weight percent, preferably from at orabout 15 to at or about 65 weight percent, more preferably from at orabout 15 to at or about 60 weight percent of the flame retardantmixture, the weight percent being based on the total weight of the flameretardant mixture, i.e. the sum of a) component b1), plus theintumescent system, plus the zeolite component b3) and wherein theintumescent system is the sum of the phosphorous-containing aminocomponent b2), the carbonific agent and the spumific agent.

The acid source b2) is a material that yields acidic species, forexample, upon heat exposure and acts as a catalyst. The acid source b2)in the intumescent system is the same as described in the precedingparagraphs above for the phosphorous-containing amino composition b2).With the aim of increasing thermal stability, improving water resistanceand improving dispersibility within the thermoplastic resin, the acidsource b2) may be coated, as described above for b2).

The carbonific agent in the intumescent system is also known as a carbonsource, char-promoting agent, char-forming agent or carbonizationcompound. The carbonific agent is an organic compound which will reactwith the liberated acidic species to yield a carbon char. The carbonificagent is preferably selected from the group consisting of polyhydricalcohols, saccharides, alkylol melamines, polyol(alkyl carbonates)phenol-formaldehyde resins, char-forming polymers, and mixtures ofthese. Examples of polyhydric alcohols include without limitationpentaerythritol, dipentaerythritol, tripentaerythritol andpolycondensates of pentaerythritol. Examples of saccharides includewithout limitation starches and their derivatives, dextrins,cyclodextrins, D-mannose, glucose, galactose, sucrose, fructose, xylose,arabinose, D-mannitol, D-sorbitol, D- or L-arabitol, xylitol, inositol,adonitol, dulcitol, iditol, talitol, allitol, altritol, guilitol,erythritol and threitol. Examples of char-forming polymers includewithout limitation polyamides, thermoplastic polyurethanes andpolycarbonates.

The spumific agent in the intumescent system is also known as a blowingagent or expanding agent and is a compound that generates non-flammablegases, such as carbon dioxide (CO₂), water, nitrogen (N₂) and ammonia,each of which causes the char to swell. The spumific agent is preferablyselected from amines, amides, ureas, guanidines, guanamines, triazines,melamines, amino acids, and salts of these. Examples of salts of amines,amides, ureas, guanidines, guanamines, triazines, melamines, and aminoacids include phosphates, phosphonates, phosphinates, borates,cyanurates and sulfates. Examples of amines and salts of these includewithout limitation ammonium phosphates, ammonium pyrophosphates,ammonium polyphosphates, ethylenediamine phosphates, ammonium cyanuratesand ammonium borates. Examples of melamine salts include withoutlimitation melamine phosphates (e.g. melamine orthophosphate, melaminediphosphate, melamine polyphosphate), melamine cyanurates, melamineborates, melamine borophosphates, melamine silicates, melamine1,2-phthalates, melamine 1,3-phthalates, melamine 1,4-phthalates,melamine guanidates and melamine oxalates.

The flame retardant polymer compositions described herein may furthercomprise additives that include, but are not limited to, one or more ofthe following components as well as combinations of these: metaldeactivators, such as hydrazine and hydrazide; heat stabilizers;antioxidants; modifiers; colorants, lubricants, fillers and reinforcingagents, impact modifiers, flow enhancing additives, antistatic agents,crystallization promoting agents, conductive additives, viscositymodifiers, nucleating agents, plasticizers, mold release agents, scratchand mar modifiers, drip suppressants, adhesion modifiers and otherprocessing aids known in the polymer compounding art. When used,additional additives are preferably present in amounts of about 0.1 toabout 20 weight percent, based on the total weight of the flameretardant polymer composition. In a preferred embodiment, the additivecomprises a high molecular weight polysiloxane. The use of a highmolecular weight polysiloxane as an additive in the flame retardantcompositions described herein improves the extrudability and theabrasion resistance of the compositions. When used, high molecularweight polysiloxanes are preferably present in amounts of about 0.05 toabout 1.75 weight percent, based on the total weight of the flameretardant polymer composition.

The flame retardant compositions disclosed herein may further compriseagents that increase softness, such as poly(meth)acrylate orpolyethylene/(meth)acrylate rubber. As used herein, the term“(meth)acrylate” refers to methacrylate and/or acrylate and the term“poly(meth)acrylate refers to polymers derived from the polymerizationof methacrylate and/or acrylate monomers. The acrylate rubber may beprepared by copolymerizing one or more (meth)acrylate monomers with oneor more olefins. A preferred olefin is ethylene. Preferably, theacrylate rubbers include poly(alkyl(meth)acrylate) rubbers,ethylene/alkyl (meth)acrylate copolymer rubbers andpoly(perfluoroalkyl(meth)acrylate) rubbers. More preferably the acrylaterubbers are ethylene/alkyl (meth)acrylate copolymer rubbers where thealkyl group has from 1 to 4 carbons. Preferredethylene/alkyl(meth)acrylate copolymers are those derived from less thanabout 80 weight percent of ethylene and more than about 20 weightpercent alkyl(meth)acrylate. The acrylate rubbers may optionallycomprise additional repeat units derived from one or more functionalizedcomonomers, such as (meth)acrylate glycidyl esters (such as glycidylmethacrylate), maleic acid, or other comonomers having one or morereactive groups including acid, hydroxyl, epoxy, isocyanates, amine,oxazoline, chloroacetate, or diene functionality. The acrylate rubbersmay also be prepared from more than two (meth)acrylate monomers.Examples are acrylate rubbers made by polymerizing ethylene, methylacrylate, and a second acrylate (such as butyl acrylate).

The additives described above may be present in the flame retardantpolymer compositions of the invention in amounts and in forms known inthe art, including in the form of so-called nanomaterials where at leastone of the dimensions of the particles is in the range of 1 to 1000 nm.The flame retardant polymer compositions described herein are melt-mixedblends, wherein all of the polymeric components are well-dispersedwithin each other and all of the non-polymeric ingredients arewell-dispersed in and bound by the polymer matrix, such that the blendforms a unified whole. Any melt-mixing method may be used to combine thepolymeric components and non-polymeric ingredients of the presentinvention.

The polymeric components and non-polymeric ingredients of the flameretardant polymer compositions of the invention may be added to a meltmixer, such as, for example, a single or twin-screw extruder; a blender;a single or twin-screw kneader; or a Banbury mixer, eithersimultaneously through a single step addition, or in a stepwise fashion,and then melt-mixed. When adding the polymeric components andnon-polymeric ingredients in a stepwise fashion, part of the polymericcomponents and/or non-polymeric ingredients are first added andmelt-mixed with the remaining polymeric components and non-polymericingredients being subsequently added and further melt-mixed until awell-mixed composition is obtained. When long-length fillers such as forexample long glass fibers are used in the composition, pultrusion may beused to prepare a reinforced composition.

The components of the intumescent additive mixture may be combined bymixing in a blender, Banbury mixer, roll mill, or any method for mixingand dispersing chemical compounds known to those skilled in the art, solong as the method does not result in degradation of the components. Thecomponents of the intumescent additive mixture may also be blendedindividually with the flame retardant additive b1) and/or thethermoplastic elastomer by a method that does not degrade theingredients of the intumescent mixture, for example in a Banbury mixeror an extruder.

Also described herein are uses of a flame retardant composition (i.e. aflame retardant mixture) comprising i) b1) the at least one flameretardant comprising a phosphinate of the formula (I); and/or adiphosphinate of the formula (II); and/or polymers of (I) and/or (II) asdescribed herein, ii) phosphorous-containing amino composition b2), andiii) the zeolite b3) described herein for imparting flame retardance andlow smoke emission to a composition comprising a) the one or morethermoplastic resins as described herein or other polymers that may bethermoplastic resins, thermoplastic elastomers or elastomers, whereinthe flame retardant composition (i.e. b1) plus b2) plus b3)) is presentin the flame retardant polymer composition in an amount from at or about18 to at or about 50 weight percent, the weight percentage being basedon the total weight of the flame retardant polymer composition andwherein b1) is present in the flame retardant polymer composition in anamount from at least 15 weight percent, preferably from at or about 15to 25 weight percent based on the total weight of the flame retardantpolymer composition, and b2) is present in the flame retardant polymercomposition in an amount such that the amount of b2) is lower than theamount of b1), preferably in an amount from at or about 5 to at or about15 weight percent based on the total weight of the flame retardantpolymer composition. Preferably, b3) is present in the flame retardantpolymer composition in an amount of at least 5 weight percent, even morepreferably in an amount from at or about 5 to at or about 20 weightpercent, based on the total weight of the flame retardant polymercomposition.

Also described herein are methods for imparting flame retardance and lowsmoke emission to an article made of a flame retardant polymercomposition, the method comprising melt blending a) the one or morethermoplastic elastomers described herein with a flame retardantcomposition comprising b1) the at least one flame retardant comprising aphosphinate of the formula (I); and/or diphosphinate of the formula(II); and/or polymers of (I) and/or (II) as described herein, b2) thephosphorous-containing amino composition selected from the groupconsisting of reaction products of ammonia with phosphoric acid,polyphosphates of said reaction products, and mixtures thereof; and b3)the zeolite described herein, wherein the flame retardant composition ispresent in an amount from at or about 18 to at or about 50 weightpercent (the weight percentage being based on the total weight of theflame retardant polymer composition), b1) is present in the flameretardant composition in an amount from at or about 30 to at or about 85weight percent, b2) is present in the flame retardant composition in anamount greater than 10 to at or about 30 weight percent, and b3) ispresent in the flame retardant composition in an amount from at or about10 to at or about 40 weight percent,

provided that the sum b1) b2) b3) is 100%, so as to form a flameretardant polymer composition and shaping said flame retardant polymercomposition.

Also described herein are methods for imparting flame retardance and lowsmoke emission to an article made of a flame retardant polymercomposition, the method comprising melt blending the intumescentadditive composition described herein, the component b1) component andthe one or more thermoplastic elastomers described herein.

The flame retardant polymer compositions described herein may be shapedinto articles using methods known to those skilled in the art, such asinjection molding, blow molding, injection blow molding, extrusion,thermoforming, melt casting, vacuum molding, rotational molding,calendar molding, slush molding, filament extrusion and fiber spinning.Such articles may include films, fibers and filaments, wire and cablecoatings; photovoltaic cable coatings, optical fiber coatings, tubingand pipes; fabrics or texiles made fibers and filaments, e.g., used inclothing or carpets; films and membranes such breathable membranes inroofing and building/construction; motorized vehicle parts such as bodypanels, air bag doors, dashboards, engine covers, rocker panels or airfilter covers; components for household appliances, such as washers,dryers, refrigerators and heating-ventilation-air conditioningappliances; connectors in electrical/electronic applications; componentsfor electronic devices, such as computers; components for office-,indoor-, and outdoor-furniture; and footwear components.

EXAMPLES

The invention is further illustrated by certain embodiments in theexamples below which provide greater detail for the compositions, usesand processes described herein.

The following materials were used to prepare the flame retardant polymercompositions described herein and the compositions of the comparativeexamples.

Copolyester Thermoplastic Elastomer (TPC): a copolyetherester elastomercomprising about 44.9 weight percent of poly(tetramethylene oxide)having an average molecular weight of about 1000 g/mol as polyetherblock segments, the weight percentage being based on the total weight ofthe copolyetherester elastomer, the short chain ester units of thecopolyetherester being polybutylene terephthalate and polybutyleneisophthalate segments. As required for the manufacturing process andwell-known to those skilled in the art, the copolyetherester elastomercontained up to 6 weight percent of heat stabilizers, antioxidants andmetal deactivators.

Phosphinate flame retardant: Exolit® OP935, an aluminum salt of diethylphosphinate having a D90 max of 7.506 microns supplied by Clariant.Melamine pyrophosphate (MPP): MelBan 13-1100 supplied by Hummel Croton,Inc., South Plainfield, N.J., USA.Coated melamine pyrophosphate: a melamine pyrophosphate coated with0.6±0.1 wt. % Silquest® A-1100 silane.Ammonium polyphosphate: Budit® 3168 supplied by Budenheim. GermanyZeolite: Zeolyst™ CBV100 supplied by Zeolyst International,Conshohocken, Pa., USA. This product is a Y type zeolite (NaY) of a FAUframework type having the following characteristics:SiO2/Al2O3 mole ratio: 5.1;nominal cation form: sodium;Na₂O weight percent: 13.0;unit cell size: 24.65 A;surface area: 900 m2 μg,

For each composition of an Example or composition of a ComparativeExample, the materials in the amount listed in Table 1 were melt blendedin a 30 mm twin screw extruder (Coperion ZSK 30) operated at a barreltemperature of about 220° C. to 240° C. using a screw speed of about 150rpm to 250 rpm and a throughput of about 6 to about 12 kg/hour. Thecompounded melt blended mixtures were extruded in the form of narrowstrips (or bands) having an average thickness as indicated in the Table.Quantities shown in the Table are presented in weight percent on thebasis of the total weight of the composition.

In the Table, compositions of the Examples are identified as “E” andcompositions of the Comparative Examples are identified as “C”. Table 1provides a list of components corresponding to compositions E1 to E6 andcompositions C1 to C3.

The following test methods were used to determine physical properties.

Flame Retardance

Flammability testing was performed according to UL 94 test standard, 20mm vertical burning test. Test specimens were prepared from thecompositions of the table by melt-extruding narrow flat strips in astandard extruder having barrel temperatures set at about 220° C. toabout 240° C. Test specimens, in the shape of rectangular bars ofdimension 125 mm long by 13 mm wide, were cut from the thus-obtainedflat strips.

Test specimens were clamped with the longitudinal axis vertical toposition the lower edge of the specimen was 300 mm above a horizontallayer of dry absorbent surgical cotton. A burner producing a blue flame20 mm high was placed so that the flame was applied centrally to themid-point of the lower edge of the specimen for 10 seconds. After theapplication of the flame to the specimen for 10 seconds, the burner waswithdrawn from the sample and the after-flame time, t₁, was measured.When after-flaming of the test specimen stopped, the burner was replacedbeneath the specimen for an additional 10 seconds. The flame was thenwithdrawn from the sample and the second after-flame time, t₂, wasmeasured. Materials were classified according to the test specificationsas V-0, V-1 or V-2, based on the behavior of the composition duringburning. When the composition failed to meet the criteria for the leastdemanding classification (V-2), it is reported as “failed” in the table.

Flammability was measured for all compositions after they had beenpreconditioned for at least 48 hours at 23° C. and 50 percent relativehumidity.

Smoke Emission Method

Equipment and Set-Up Method

The equipment included a heat source which was a laboratory burneraccording to UL 94 standard “Tests for Flammability of Plastic Materialsfor Parts in Devices and Appliances”. Gas supply—a supply of technicalgrade methane gas with regulator and meter for uniform gas flow.

The sample holder was a porcelain crucible which was inert to thematerial being tested. The crucible had a height of 36 mm and anexternal to diameter of 45 mm (model VWR 102/45 DIN). The crucible wasplaced within a triangular porcelain holder having a height of 47 mm andsides of 56 mm. The triangular holder was attached via wire means onto athree-legged support having a height of 220 mm, an external diameter of170 mm and a wall thickness of round section of 15 mm. The height of thecrucible with respect to the laboratory burner was adjusted so that thetop of the flame touched and was centrally positioned to touch thebottom of the crucible. A round piece of aluminum foil of externaldiameter 120 mm having a center circular hole of 44 mm diameter andsufficient to fit the crucible was placed atop the triangular holder.

A glass chimney having a total height of 300 mm, a bottom insidediameter of 100 mm, a height of cylinder before striction of 270 mm, anda top inside diameter of 50 mm was placed atop and in direct contactwith the aluminum foil. A plastic cone having holes was fitted into thetop section of the glass chimney; the cone having a bottom insidediameter of 46 mm, a top inside diameter of 32 mm, a height of 94 mm anda height remaining above the top surface of the chimney of 68 mm; thecone had 22 open holes of diameter 5 mm. A metal plate was placed atopthe upper surface of the plastic cone, the metal plate having dimensionssuch that it was at least as large as the upper surface of the plasticcone. The glass chimney was supported in place by means of at least onepoint fixed to a vertical metal stand.

A photometric system of the following type was also used—Light Source:Model Makita ML700 flashlight; Lens diameter 21 mm; Power 7.2V, capacity1.3 Ah. Receiver—Photocell: Glass-EVA-cell-EVA-glass laminated system.The EVA was a Vistasolar® film type 486.10 from ETIMEX Solar GmbH(Dietenheim, Germany); the cell was a polycrystalline silicone cell fromQ-cells AG type Q6LTT-180/1410 having an edge length of 156 mm and anefficiency of >=14.1%. Standard lamination conditions at 140° C. for 18minutes were followed. The photocell was Kapton® taped at the edges andhad a final dimension of 200 mm×200 mm.

For data collection, an Oscilloscope Model LeCroy 9304 Quad 175 MHz wasused. The light source and the receiver were placed on the left andright side respectively of the glass chimney and in the center of thechimney walls. The distance between the light source and the outer leftsurface of the chimney was 160 mm and the distance between the outerright surface of the chimney and the receiver was 360 mm. The receiverwas connected to the oscilloscope and the signal output in volts wasrecorded.

All equipment except the oscilloscope was placed inside a laboratoryfume hood according to UL 94 standard “Tests for Flammability of PlasticMaterials for Parts in Devices and Appliances”. The fume hood used wasfrom Atlas Fire Science Products, Plastics HVUL. To preventconcentration of fumes inside the hood a light aspiration was maintainedin the fume hood. A protection shield was placed around the laboratoryburner to prevent any instability in the flame. After completion of eachmeasurement the fume hood ventilation system was opened to permitcomplete exhaust of the fumes.

Examples 1 to 6 and Comparative Examples C1 to C3

Table 1 shows that composition C1, comprising only a phosphinate flameretardant, exhibited flame retardance but minimum light transmission,i.e. “0.15” indicating relatively high smoke emission. The compositionsC2 and C3 contained the same amount of flame retardant as C1 andcontained zeolite. C2 and C3 exhibited high smoke emission.

E1 to E6 exhibit good flame retardance and improved smoke emissionrelative to C1, C2 and C3.

TABLE 1 C1 C2 C3 E1 E2 E3 E4 E5 E6 TPC 85 83 80 75 72 75 72 75 72Exolit ® OP935 15 15 15 15 15 15 15 15 15 Coated melamine pyrophosphate5 8 Uncoated melamine pyrophosphate 5 8 Zeolite 2 5 5 5 5 5 5 5 Budit ®3168 5 8 UL-V (t1 + t2)avg (sec) 3.33 3 6.66 3 8.7 5 4.7 16 11.7 UL-Vrating V-0 V-2 V-2 V-2 V-2 V-2 V-2 V-2 V-2 Band thickness avg (mm) 1.81.8 1.6 1 1.8 1 1.1 2 1.5 (lt/lo)sample 0.15 0.12 0.13 0.38 0.42 0.300.20 0.50 0.61 (lt/lo)ref 0.69 0.69 0.69 0.69 0.69 0.69 0.69 0.69 0.69

1. A flame retardant polymer composition comprising: a) one or morethermoplastic elastomers; and b) from at or about 18 to at or about 50weight percent, based on the total weight of the flame retardant polymercomposition, of a flame retardant mixture comprising: b1) at least oneflame retardant comprising a material selected from the group consistingof phosphinates of the formula (I); diphosphinates of the formula (II);polymers of (I); polymers of (II); and mixtures of two or more thereof

wherein R₁ and R₂ are independently selected from hydrogen, linear orbranched C₁-C₆ alkyl groups, and aryl groups; R₃ is a linear or branchedC₁-C₁₀-alkylene group, a C₆-C₁₀-arylene group, an alkylarylene group oran arylalkylene group; M is selected from the group consisting ofcalcium, magnesium, aluminum, zinc and mixtures thereof; m is 2 to 3; nis 1 or 3; and x is 1 or 2; b2) a phosphorous-containing aminocomposition selected from the group consisting of melamine phosphates,derivatives of melamine phosphates and mixtures thereof, reactionproducts of ammonia with phosphoric acid, polyphosphates of saidreaction products, and mixtures thereof; and b3) a zeolite, wherein i)b1) is present in the flame retardant polymer composition in an amountgreater than or equal to 15 weight percent based on the total weight ofthe flame retardant polymer composition, and ii) b2) is present in theflame retardant mixture in an amount such that the amount of b2) is lessthan the amount of b1).
 2. A flame retardant polymer compositionaccording to claim 1, wherein the one or more thermoplastic elastomersare copolyetherester elastomers having a multiplicity of recurringlong-chain ester units and short-chain ester units joined head-to-tailthrough ester linkages, said long-chain ester units being represented byformula (A):

and said short-chain ester units being represented by formula (B):

wherein: G is a divalent radical remaining after the removal of terminalhydroxyl groups from poly(alkylene oxide)glycols having a number averagemolecular weight of between about 400 and about 6000; R is a divalentradical remaining after removal of carboxyl groups from a dicarboxylicacid having a molecular weight of less than about 300; and is a divalentradical remaining after removal of hydroxyl groups from a diol having amolecular weight less than about
 250. 3. A flame retardant polymercomposition of claim 2, wherein the one or more thermoplastic elastomersare copolyetherester elastomers prepared from monomers comprising (1)poly(tetramethylene oxide) glycol; (2) a dicarboxylic acid selected fromthe group consisting of isophthalic acid, terephthalic acid and mixturesthereof; and (3) a diol selected from the group consisting of1,4-butanediol, 1,3-propanediol and mixtures thereof.
 4. A flameretardant polymer composition of claim 2, wherein the one or morethermoplastic elastomers are copolyetherester elastomers prepared frommonomers comprising (1) poly(trimethylene oxide) glycol; (2) adicarboxylic acid selected from the group consisting of isophthalicacid, terephthalic acid and mixtures thereof; and (3) a diol selectedfrom the group consisting of 1,4-butanediol, 1,3-propanediol andmixtures thereof.
 5. A flame retardant polymer composition of claim 2,wherein the one or more thermoplastic elastomers are copolyetheresterelastomers prepared from monomers comprising (1) ethylene oxide-cappedpolypropylene oxide)glycol; (2) dicarboxylic acids selected from thegroup consisting of isophthalic acid, terephthalic acid and mixturesthereof; and (3) a diol selected from the group consisting of1,4-butanediol, 1,3-propanediol and mixtures thereof.
 6. A flameretardant polymer composition of claim 1, wherein the at least one flameretardant b1) is selected from the group consisting of aluminumphosphinate, diethyl phosphinate and/or zinc diethyl phosphinate.
 7. Aflame retardant polymer composition of claim 1, wherein the zeolite b3)is represented by the general formulaM_(2/n)O.Al₂O₃ .xSiO₂ .yH₂O wherein M is a metal selected from alkaliand alkaline earth metals, V, Mo, Mn, Fe, Co, Ni, Cu, Zn, Sb, Bi andmixtures thereof; n is the cation valence; x lies between 0.1 and 20;and y is the number of moles of water of crystallization and has a valueof 0 to
 20. 8. A flame retardant polymer composition of claim 1 whereinthe amount of zeolite b3) is greater than or equal to 5 weight percent,based on the total weight of the flame retardant polymer composition. 9.A flame retardant polymer composition of claim 1 wherein b2) is selectedfrom melamine pyrophosphate or ammonium polyphosphate.
 10. A flameretardant polymer composition of claim 1 wherein thephosphorous-containing amino composition comprises ammoniumpolyphosphate.
 11. A flame retardant polymer composition of claim 1wherein b3) is present in the composition in an amount greater than orequal to 5 weight percent based on the total weight of the flameretardant polymer composition.
 12. A flame retardant polymer compositionclaim 1 wherein the flame retardant mixture b) comprises b1) which ispresent in the flame retardant polymer composition in an amount from ator about 15 to 25 weight percent based on the total weight of the flameretardant polymer composition, b2) is present in the flame retardantpolymer composition in an amount from at or about 5 to 15 weight percentbased on the total weight of the flame retardant polymer composition andb3) is present in the flame retardant polymer composition in an amountfrom at or about 5 to 20 weight percent based on the total weight of theflame retardant polymer composition.
 13. A molded, extruded, or shapedarticle and a fiber or a filament comprising the flame retardant polymercomposition recited in claim
 1. 14. A wire, a cable or an optical cablecomprising a coating made of the flame retardant polymer compositionrecited in claim
 1. 16. A flame retardant composition comprising A) atleast one flame retardant comprising a material selected from the groupconsisting of phosphinates of the formula (I); diphosphinates of theformula (II); polymers of (I); polymers of (II); and mixtures of two ormore thereof;

wherein R₁ and R₂ are independently selected from hydrogen, linear orbranched C₁-C₆ alkyl groups, aryl groups and mixtures thereof; R₃ is alinear or branched C₁-C₁₀ alkylene group, a C₆-C₁₀ arylene group, analkylarylene group or an arylalkylene group; M is selected from thegroup consisting of calcium, magnesium, aluminum, zinc and mixturesthereof; m is 2 to 3; n is 1 or 3; and x is 1 or 2; B) aphosphorous-containing amino composition selected from the groupconsisting of reaction products of ammonia with phosphoric acid,polyphosphates of said reaction products, and mixtures thereof; and C) azeolite wherein A) is present in the flame retardant composition in anamount from at or about 30 to at or about 85 weight percent, ii) B) ispresent in the flame retardant composition in an amount greater than 10to at or about 30 weight percent, and iii) C) is present in the flameretardant composition in an amount from at or about 4 to at or about 40weight percent, provided that the sum A)+B)+C) is 100 weight percent.17. The flame retardant composition of claim 16 wherein thephosphorous-containing amino composition comprises ammoniumpolyphosphate.
 18. A flame retardant polymer composition comprising fromat or about 18 to at or about 50 weight percent of the flame retardantcomposition of claim 16 and a polymer, wherein the weight percentage isbased on the total weight of the flame retardant polymer composition.19. A process for imparting flame retardance and low smoke emission to acomposition comprising one or more thermoplastic vulcanizates, theprocess comprising the step of mixing the flame retardant composition ofclaim 16 and a thermoplastic elastomer.